Fire alarm



April 24, 1951 L. H. MOCARRON FIRE ALARM Filed NOV. 8, 1948 LEW/S H.MCCARPON,

1N VEIY TOR.

' ATTORNEK Patented Apr. 24, 1951 UNITED STATES PATENT OFFICE FIRE ALARMLewis H. McCarron, Los Angeles, Calif.

Application November 8, 1948, Serial No. 58,869

3 Claims. (Cl. 179-5) The invention relates to a fire alarm for use withthe ordinary dial telephone system.

While fire alarms of this general type have been proposed heretofore,some of them fall to consider that the telephone line may be dead, 5.that is, with no idle trunk available, at the start, hence when thealarm dials a particular number, some of the dialing impulses are lostwhich results in dialing a wrong number.

Certain other alarm systems of this general type are very complicated,and propose to dial a special signal over a special trunk line.

The present invention provides a fire alarm which takes advantage of thefact that the operators line number 111 has not been assigned for useand it takes further advantage of the fact that it is not necessary todial a special signal over a special trunk line, because the operatorcan identify any line which is calling.

The present invention overcomes the fact that the telephone line may bedead at the start, by dialing a prolonged series of impulses which ineffect dials the number 111 in succession.

The alarm of this invention is so arranged that the dialing contacts donot interfere with the, normal use of the telephone and are brought intoplay when a fire occurs, by an improved simple mechanism wherein athermostat directly controls an escapement device for the dial of thefire alarm.

For further details of the invention reference may be made to thedrawings wherein- Fig. 1 is a diagrammatic illustration showing the firealarm of this invention connected to a conventional subscribers dialtelephone.

Fig. 2 is a schematic elevation of the thermostat control of Fig. 1,with parts broken away.

Fig. 3 is a schematic circuit showing the fire alarm in circuit with theusual dial telephone.

Referring in detail to the drawings, in Fig. 1 40 the usual subscribersdial telephone is indicated at I as having the usual stand 2, handset 3and dial 4. The usual cord connecting the stand 2 to the handset 3 isnot illustrated. Connected to the stand 2 is the usual telephone line69, 10.

The invention provides a special dial Ill having contacts I l which areshown in Fig. 3 as connected by Wire 12, through impulse switch BI andtransmitter 62 to line 69, and by wire |3 to line 10, hook switch 63being open. The contacts ll 50 in this case are open when the fire alarmis idle so as not to interfere with the ordinary use of the telephone.

As shown in Fig. 1, the contacts l comprise an upper contact |4connected to a strip l5 and a 65 lower contact I6 connected to a springstrip H. The strips l5 and I1 are suitably secured to an insulatingblock l8. Strip I5 has a suitable terminal I9 connected to the line l2and strip I1 has a suitable terminal 29 connected to line l3.

Strip I! has a downwardly facing convexportion 2| which serves as a camfollower for the cams 22 on the dialing wheel 23. The cams 22 form acomplete sinusoidal series around the periphery of the wheel 23. Whenwheel 23 rotates, each lobe like 24actuates the cam follower 2| to closethe contacts II and send a dialing impulse over the telephone lines SI],10.

The cam follower 2| may be adjusted in position with respect to anyparticular lobe 24 at the top of wheel 23 as the block it and itscontact strips I5 and H; are carried by a bracket 3| which has anaperture 3| to receive a bolt 32 having locknuts 33 and 34. This bolt 32is carried by a suitable support indicated at 35. Bracket 30 isadjustable to move cam 2| along the periphery of wheel 23. Also theblock I8 and contacts H can be moved toward or away from the wheels 23,as bracket 30 forms a pivotal support therefor, indicated at 31, bracket3|] also having adjusting screws 38 and 39 which bear on the oppositesides of the strips l5 and I! to angularly adjust the position of thecam follower 2|.

Wheel 23 has fixed thereto a gear 49. Fixed to gear 40 is a pinion 4|which meshes with a ear 42 driven by a spring indicated at 43. Spring 43may be wound up by means well known and not illustrated. When spring 43unwinds, it rotates gear 42 in a counter-clockwise direction asindicated by arrow 44, to drive the wheel 23 clockwise. Rotation ofwheel 23 is controlled as follows. Gear 40 meshes with a pinion 45having fixed thereto a ratchet wheel 46 having an escapement pawl 41which oscillates on a pivot indicated at 48. Pawl 41 has an arm 49. Thethermostat when idle has an outer end 5| which serves as an abutment orstop which bears against the arm 49 to prevent operation of the pawl 41.The thermostat 5|] is located at a suitable place in the building. Whena fire occurs, the thermostat 50 expands, whereby its outer end 5| movesaway from the arm 49 as shown in Fig. 2, to release the pawl 41 andpermit the spring 43 to drive the wheel 23.

The speed of operation of the pawl 41 is regulated by means of a slidingweight, here shown as a nut 52 on a bolt 53 fixed to and projecting fromthe pawl 41.

A duplicate of the above fire alarm can of course be located at variousother places in a building, all of such alarms being connected to thelines I2, l3.

Various modifications may be made in the invention without departingfrom the spirit of the following claims. For example, the line l3 may beconnected to line 10 through a switch contact controlled by hook switch63, such contact being closed or open as the receiver is off or on thehook, respectively, to disconnect the fire alarm when its receiver isremoved.

The invention is quite simple as the contacts I l are directly connectedto the telephone and the thermostat 50 directly controls the escape 46,41 for the dialing wheel 23.

As the wheel 23 has an uninterrupted series of sinusoidal peaks like 24,the wheel 23 when released by the thermostat 50, will in effectrepeatedly dial the number 111 so that this will come to the attentionof a special operator who can be assigned to the line 111 at the centralstation. Such operator has facilities for quickly identifying thecalling line and thereupon can attempt to put through a telephone callto the building where the fire alarmis in operation to see whethersomeone is present there to put in a fire alarm or take necessary steps.In the event that the subscriber does not answer such call, the operatorcan identify the calling line and its address and put in a fire alarm. Y

I claim:

1. Fire alarm apparatus for a dial telephone system having automaticswitching equipment and a special line, said apparatus comprising dialmeans for producing dialing impulses in a prolonged series of unitdigits, means for supplying said impulses to a subscribers line of saidsystem to operate the automatic switching equipment of said system andselect said special line, a motorfcr said dial means, an escapement forcontrolling operation of said motor and a thermo-responsive movableabutment for controlling said escapement.

2. Fire alarm apparatus comprising dial contacts, a dial wheel foroperating said contacts, a motor for driving said wheel, anuninterrupted series of dialing projections around said wheel, a ratchetwheel, for said dial wheel, a pawl for said ratchet wheel, an arm onsaid pawl and a bimetallic strip having a free end, and means supportingsaid strip with said free end in position to abut said arm at certaintimes and not at other times as influenced by temperature.

3. Fire alarm apparatus comprising dial contaste, a dial wheel foroperating said contacts, a motor for driving said wheel, anuninterrupted series of dialing projections around said wheel, abimetallic strip having a free end, means restraining operation of saidmotor, and means supporting said strip with its free end in position asa movable abutment controlling said restraining means.

LEWIS H. M'oCARRON.

REFERENCES CITED The following references are of record in the file ofthis patent. 7

UNITED STATES PATENTS

